Your Reusable Shopping Bags Are Teeming With Bad Bacteria

Pop quiz! When was the last time you washed your reusable shopping totes? You know, the ones kicking around in the trunk of the car or the bottom of a backpack. The ones you cram full with fruits, vegetables, a carton of eggs from pastured hens, grass-fed beef, and other goodies. The ones you set down on the pavement or in a shopping cart and then plop on top of your kitchen counter.

Maybe, like, never? I thought so.

Well, you are not alone. Most shoppers who have switched from store-provided flimsy plastic or paper bags to sturdier reusable ones rarely, if ever, wash them. Any food-safety professional or microbiologist will tell you, however, that those unwashed bags are teeming—absolutely teeming—with the baddies of the bacteria world, including E. coli 0157:H7 and other pathogens that cause food-borne illnesses. It’s also worth noting that all food, whether conventional or certified organic, is susceptible.

Yes, it’s true that when it comes to recalls, most of the problems stem from a food or ingredient that’s already contaminated by the time it reaches the consumer. But it’s also true that no matter how carefully a producer follows growing and handling protocols, he or she can’t control—for example—the none-too-clean hands of John Q. Public, who feels obliged to fondle every single tomato or paw through an entire heap of green beans before making a selection. You should also know that salmonella may be found in organic eggs or those from hens that freely hunt and peck on pasture, as wild birds and rodents are among the other carriers of the bacteria.

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That’s why we all have a responsibility to help prevent cross-contamination—that is, the spread of harmful bacteria from a contaminated food to one that’s uncontaminated. I suppose an unwashed tote isn’t much worse than a kitchen sponge and a damp, infrequently changed dish towel—two ideal homes for microbes—but why not be proactive, especially in the summer, when we serve so many raw fruits and vegetables? Here’s the rundown on the best way to clean reusable bags made from various materials.

When cleaning the food inside those bags, there are a few options. A thorough rinsing under running water will remove most microbial contamination, along with dirt and most surface pesticide residues and waxes. As for expensive fruit and vegetable washes, sources ranging from the FDA to Cook’s Illustrated—which have put various cleaning methods through their paces—advise you to save your money.

The FDA recommends thoroughly washing all produce (including those bought at a farmers market or grown at home) under running water, which is more abrasive than simply soaking fruits or vegetables in a bowl of water; drying them with a clean kitchen towel or paper towel further reduces surface bacteria. You can also scrub firm produce such as muskmelons (what most people know as cantaloupes) with a clean produce brush; otherwise, it’s easy to transfer surface microbes to the interior when slicing.

The folks at Cook’s Illustrated take things a step further by making their own produce wash for the price of pennies. “A spray bottle filled with three parts water and one part white vinegar works just as well [as a commercial wash] to clean smooth-surfaced produce such as apples and pears. Just spray, then rinse under tap water. In our tests, this method removed 98 percent of surface bacteria,” they concluded.

Fruits and vegetables will keep longer in the fridge if you wash them just before using. This is particularly true for fragile produce such as strawberries and raspberries. That said, I tend to wash my salad greens all at once and ahead of time. In the throes of getting supper on the table, it’s the last thing I want to do, so I find myself putting off salad making until the next night and then the next.... You get the picture. I’m also fussy about using greens that are completely dry in a salad (otherwise, a dressing will not cling), but again, that’s tough to pull off when you're rushing. I whiz my washed greens in a salad spinner, then spread them out on clean tea towels to dry a bit more before loosely rolling them up in the towels and tucking them into perforated plastic bags.

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One cutting-edge device that hasn’t yet made it to home kitchens but has generated a great deal of interest is the ultraviolet light oven developed by Haiqiang Chen, a professor of food science at the University of Delaware’s College of Agriculture and Natural Resources. Chen’s invention is about the size of a microwave oven, has a simple control panel, and combines UV light with stirred-up water to rid fresh produce of pathogens, according to a July 24 report in Food Safety News. Although the device is called an oven, it will not heat the produce or have a negative effect on flavor or texture.

“The UV will kill pathogenic bacteria and viruses, but the bad thing about UV is that it doesn’t penetrate through solids, although it can penetrate through clear water,” Chen is quoted as saying. “The water will wash off the pathogens from a food surface and whenever they get into the water, they will be killed almost immediately.”

Chen’s treatment is not the same thing as irradiation, another food-safety method that’s been in use since the 1960s. As I wrote a couple of years ago, irradiation involves subjecting certain foods (typically spices, some fruits, and a limited amount of meats) to intense doses of ionizing radiation in the form of gamma rays, X-rays, or electron beams before sending them to market.

“The UV light treatment, unlike ionizing radiation, does not carry enough energy to ionize atoms,” Chen explained in an email. “It is commercially used to treat drinking water and apple cider to improve their microbial food safety in the United States.”

No one is suggesting that the food industry should regard this technology as a substitute for stringent sanitation protocols and thus the prevention of contamination in the first place. But one day it could be an additional safeguard for home cooks as well as restaurants, cafeterias, commercial kitchens, and hospitals.